A station for loading a roll changer is known from EP 0 227 887 A2, in which a material roll is moved on a transport structure into position between roll support arms having clamping jaws, where it is raised by the transport structure. Various sensors are used for transverse centering and to detect the alignment of the roll axis and the center axis of the clamping jaws, and to register and to control the advancement of the transport structure in a horizontal direction.
EP 03 91 061 A1 describes a system for loading a roll changer. A material roll is first placed in a rough adjustment position, and then is placed in a fine adjustment position, separately from the roll changer. The fine adjustment position corresponds to the position of the loading cones in the roll changer. In this fine adjustment position, the material roll is held in place on a transport structure, and is then moved into the roll changer in a horizontal direction, by use of the transport structure.
DE 37 31 488 A1 relates to a device for clamping a replacement web of material. Various sensors ensure a precise positioning of the rolls below the clamping point. Sensors also determine the diameter of the replacement roll, from which diameter determination the sensors then determine the necessary clamping height. If necessary, the roll of material is raised to the necessary height by the use of a lifting device. The roll core is detected by a photoelectric sensor, and additional sensors detect the position of the roll when it reaches the roll changer.
DE 38 22 572 C2 describes a roll unwinding device for wound rolls of web-type material. The device enables the utilization of an automatic process for orienting the wound roll, taking into account the actual position of the core ends, without requiring the provision of a separate measuring station.
In U.S. Pat. No. 4,131,206 A, an automatic device for supplying a roll of material in a rotary printing press is described. Through the use of a dual-truck mechanism, a new roll of material is transported to the printing press, where it is clamped in the roll support via automatic positioning, and the empty core is removed. Sensors determine the parameters and the position of the roll, and enable an automatic removal of the empty core from the axle.
WO 89/08598 A1 shows a device for orienting a material roll prior to loading the roll on the axle in a roll changer. A transfer table is arranged with a transport carriage that can be moved thereon. The table can be moved transversely to a longitudinal axis of the material roll, between two bearing journals of the roll changer. The transfer table is arranged so as to transport the material roll into position between two bearing journals of the roll changer. The transfer table enables a displacement of the material roll along its longitudinal axis and a pivoting of the material roll around its longitudinal axis. Elements for detecting the position of the material roll are provided. The position detection devices are arranged so as to detect an oblique position of the material roll arranged on the transfer table.
DE 43 34 582 A1 discloses a roll changer, whose bearing arms and transfer table are positioned based upon a determined roll size.
Problems arise when the position of the roll, that has been pre-adjusted in this manner, is altered by external forces with the transfer table as it is being moved into the roll changer, or when, as a result of winding errors on the core, the pre-positioning cannot be precisely guaranteed. Especially in the case of large roll widths, this roll position alteration frequently leads to problems in loading of the roll onto the axle of the roll changer. In addition, these wide rolls are subject to other dimensional tolerances, thus making a precise positioning of the roll, during loading of the roll onto the axle, even more important.